Magnetic proximity switches are used, for example, to sense the position of an industrial valve, for example in nuclear power plants. A magnet or magnetic material called a “target” may be mounted on the valve stem. A magnetic proximity switch is located adjacent to the valve stem so that the target moves within a given distance of the switch when the valve is in a given position, such as fully open or fully closed. The target in this position attracts a magnet in the switch, which closes and/or opens electrical contacts in the switch, resulting in a signal being communicated to a controller. Two proximity switches may be used—one for the open valve position and one for the closed valve position. In this configuration the two switches can confirm each other and can verify that full opening or closing has occurred. An example of such a switch is described in U.S. Pat. No. 7,489,217.